Factors associated with pain after non-surgical treatment for trapeziometacarpal joint osteoarthritis

Introduction: Although non-surgical treatment for trapeziometacarpal joint (TMJ) osteoarthritis (OA) reduces pain, outcomes vary substantially. This study investigated factors associated with pain at 3 months after starting non-surgical treatment for TMJ OA. Methods: This secondary analysis from a previous randomized controlled trial included 113 patients (Eaton–Glickel stage ⩾2 TMJ OA) from 18 outpatient hand surgery clinics in The Netherlands, comprising specialized clinics, regional hospitals and one academic hospital. Participants were randomized to orthosis-only or orthosis + exercise groups. Both groups received a standardized custom-made thumb orthosis, and the combined group also received supervised hand therapy with a structured home exercise programme. The primary outcome was the Michigan Hand outcomes Questionnaire (MHQ) pain subscale at 3 months, which was modified so that higher scores indicated less pain. We used linear regression analysis to investigate the association of baseline pain, psychological factors, outcome expectations, adherence to therapy, perceived attention, patient experience with care, treatment frequency and changes in grip and pinch strength with MHQ pain. Results: Better MHQ pain score at baseline, higher baseline outcome expectations and improvement in grip strength after 3 months were associated with better pain outcomes. The MHQ pain baseline score had the strongest independent association. Conclusion: Baseline pain severity, outcome expectations and grip strength are associated with pain at 3 months after the use of orthoses with or without exercise therapy for TMJ OA.